This invention relates to an assisted steering device for a vehicle, comprising control means acting on direction changing means, the said control means having a transmission element in two parts which are capable of limited relative angular movement which results in angular offsetting of the said parts under the action of the control means, and assistance means which, in response to this angular offsetting, are operable to act on the direction changing means in the same sense as the control means.
The arrangements proposed hitherto for providing and limiting this relative angular movement are generally fragile and/or complex in construction.
Such arrangements consist, for example, of a linchpin provided on one of the parts and engaging in an opening in the other part. However, this arrangement reduces the strength of the construction.
It has also been proposed to provide external teeth on one of the parts and to engage them with narrower internal teeth of the same pitch which are provided in a blind bore in the other part. This other part has a larger external diameter at the location of the blind bore, which makes it more complex in form and increase its radial dimensions. Moreover, the provision of internal teeth or grooves in a blind bore is difficult to accomplish and presents the problem of removing all the material machined out from the bottom of this blind bore.
The present invention provides an assisted steering device which does not have these drawbacks and in which the limited relative angular play between the two parts of the transmission element is provided in a particularly simple and robust manner.